Weatherproof seals for jamb liners for double-hung window sash remain unsatisfactory in spite of the many variations that have been tried. A suitable seal must fit well against the sash, seal against the trim stop, accommodate manufacturing tolerances in both the seal and the sash, and yet not unduly increase the effort necessary to raise and lower the sash. The seal must also be wind resistant and tolerant of temperature extremes. Finally, cost is very important in the highly competitive window business, and a suitable seal must do its job without hardly adding to the expense.
We have devised a solution that meets all these requirements. Our extruded resin jamb liner not only has suitable flexible flange seals, but also can be formed at nearly the same price as conventional jamb liners with ineffective seals. Our invention thus offers added sealing advantages at a competitive price.